Hey guys, so recently in practice I blew a power valve in my Framus Cobra 100 watt head. I've owned the amp for about 3 months now (there's only been one previous owner). I'm just curious, just exactly how hard is it to blow a power valve? It's got me a little worried there may be some fault with my amp as I never abuse it, never really crank it too high and its only getting light - medium use (Around 5 - 6 hours a week). The guy I bought it from said that the valves were fairly new and it had been serviced. I know sometimes valves can just blow, but if anyone has any particular knowledge on this, it'd still be good to know.
Unless you find it happens multiple times and quite frequently you shouldn't need to worry. One time isn't enough to be sure, just get a new matched or quad set and use your current working ones as spares.